Agenus has announced final results from a single-arm, multi-institutional, open-label, phase 2 study showing that patients with newly diagnosed glioblastoma multiforme (GBM) who received Agenus’ Prophage autologous cancer vaccine added to the standard of care treatment, lived nearly twice as long as expected.

In this phase 2 study, 50% of the patients lived for two years, an encouraging result for a cancer that often kills patients within one year. Prophage patients demonstrated a median overall survival of approximately 24 months and 33% of patients remain alive at two years and continue to be followed for survival.

“These data suggest that Prophage is generating an effective immune response which is translating into an extension in survival far beyond what is historically seen in patients with glioblastoma multiforme. These data provide the impetus for a definitive, randomised clinical trial,” says Andrew Parsa, principal investigator of the study and the Michael J Marchese professor and chair of the Department of Neurological Surgery at the Feinberg School of Medicine at Northwestern University. “Glioblastoma tumours are often resistant to standard therapies and the extended progression-free survival and proportion of long-term survivors is very encouraging.”

In addition to the long-term survival data, vaccine treated patients had a median progression-free survival (PFS) of nearly 18 months, approximately two to three-times longer than patients treated with radiation and temozolomide alone. Importantly, 22% of patients were alive and without progression at 24 months and continue to be followed for survival.

Interestingly, the response to Prophage seems to be more pronounced in those patients with less expression of the checkpoint ligand PDL-1 on the white blood cells, suggesting that combinations of Prophage with checkpoint modulators like PD-1 antagonists might make Prophage even more effective in a greater percentage of patients with glioblastoma multiforme.

“We believe that Prophage may play an important role in changing the treatment paradigm for patients with glioblastoma multiforme,” says Garo Armen, chief executive officer and chairman of Agenus. “We are exploring partnerships for phase 3 studies of Prophage in glioblastoma multiforme. Additionally, we are excited about the potential combinations of Prophage with PD-1 antagonists and other checkpoint modulators in glioblastoma multiforme.”

Prophage is an autologous cancer vaccine, and each patient receives vaccine prepared from their own surgically resected tumour. As a result, the vaccine appears to help stimulate the patient’s immune system to attack the tumour based on the spectrum of mutant proteins expressed by their own tumour. Since most cancers result from an accumulation of random mutations, which produce different mutant proteins in each patient, this approach is intended to individually tailor each patient’s vaccine to optimally target the immune attack to that patient’s actual tumour.